Breast-conserving surgery (BCS) is commonly defined as the surgical removal of a breast tumor with a safe margin of normal tissue. When supplemented with radiation therapy, BCS is generally referred to as breast-conserving therapy, or BCT. Local recurrence of breast cancer is a serious increased risk in patients undergoing BCS. For example, Atkins and colleagues have shown that the local recurrence rate following local excision was 16%, compared with 8% following mastectomy, even when supplemented with radiotherapy and chemotherapy5. Since the objective of BCS is not to leave any cancer behind in the breast, obtaining tumor-negative margins when performing BCS is the standard of care to minimize the risk of local recurrence6. Despite the attempt to achieve negative margins, primary excision for BCS yields histologically positive margins 20% to 55% of the time7. Furthermore, permanent section histopathology, the gold standard of determining margin status, is generally not available until well after the patient has left the operating room. As a result, a high percentage of patients (20 to 55% of patients with positive margins in primary excision) must return to the hospital for surgical re-excisions. Intra-operative methods of margin assessment, which are designed to provide information on margin status while the patient is still on the operating table, have so far been of limited clinical value. The long-term objective of this research is to improve the sensitivity and specificity of intra-operative margin assessment techniques for breast tissue specimens excised during BCS, and thus reduce surgical re-excision rates associated with this procedure. Phase I study objectives are: Specific Aim 1: Design and develop a surgical specimen container optimized for BCS. Specific Aim 2: Develop simulated excised breast tissue specimens with embedded simulated microcalcifications, nodules and fibers, which realistically depict both the physical and x-ray imaging characteristics of actual clinical breast tissue specimens. Specific Aim 3: Perform the pre-clinical evaluation of the specimen container against established clinical requirements of BCS utilizing simulated excised breast tissue specimens. We propose to quantify the efficacy of this tool with respect to: orthogonal x-ray imaging of specimens; providing optimal compression of specimens; and its ability to retain the three dimensional spatial orientation of the specimen from the time the specimen is excised in the operating room to the time the specimen is delivered to the Pathology Department. [unreadable] [unreadable] [unreadable]